Here the 1837 edition added the before Lamanites. This change may have been accidental. Elsewhere in the text we have one other occurrence that supports the 1837 reading: “and there is none save it be the Lamanites” (Ether 4:3). In this passage Moroni once more refers to his being alone. Yet in the Ether 4:3 passage, Moroni does not refer to the robbers. Everywhere else in the text where Lamanites is conjoined with robbers, we find that the conjoined elements always have the same parallel construction; either both have the definite article the or neither do:
Thus Mormon 8:9, if it is to read consistently with the rest of the text, should not have the intrusive the. The critical text will restore the original reading without the the.
Summary: Remove the intrusive the in Mormon 8:9, restoring the original phraseology “save it be Lamanites and robbers”.